ECLIPSES AND TRANSITS
I've updated the HeyWhatsThat Eclipse site
http://www.heywhatsthat.com/eclipse.html
for Sunday's solar eclipse, the June 4 lunar eclipse, and the June 6
transit of Venus.
To use the site, first install the Google Earth plug-in from
earth.google.com/plugin/. The plug-in brings Google Earth into your
browser. Then go to http://www.heywhatsthat.com/eclipse.html and hit
the play arrow (on the left end of the green timeline running along
the bottom of the page).
Select other simulations by using the dropdown menu labelled "Other
eclipses" at the bottom right of the page.
The Cosmic Visibility site http://www.heywhatsthat.com/cosmic.html,
which displays astronomical events using the sky images provided by
Google Maps, and the Planisphere http://www.heywhatsthat.com/ap.html,
where you can generate KML files for the night sky view in the desktop
version of Google Earth, are also ready for these events.
ECLIPSE SITE DETAILS
The eclipse page shows the Earth on the left and the sky on the right.
In the sky pane you'll see the positions of the relevant celestial
objects and the horizon. For total and annular solar eclipses, the
Earth pane shows the area that will see the total eclipse at any given
moment. If you click on "show penumbra" it will also show the much
larger region that will see just some of the Sun blocked by the Moon.
Click anywhere on the Earth to set a new viewer location, and click on
the timeline to set the time.
For the transit of Venus and lunar eclipses, the Earth pane on the
left is not important. Because I use geocentric positions for Venus
and the Sun, setting a viewer location has no effect on the simulation
of the Venus transit. I do use topocentric positions for the Moon and
the Earth's shadow, but because they're in the same physical location
in space, you'll find that setting a viewer location for a lunar
eclipse only changes the location of the Moon and Earth's shadow
against the background of the stars, not their relative positions.
RUNNING AND CYCLING ROUTES: RISE AND FALL
At the profiler test site
http://www.heywhatsthat.com/profiler-0904.html
click the checkbox labelled "show rise/fall" on the right side of the
page and you'll see the total rise and total fall in elevation for
each leg of the path. For example, if your path goes up 100 feet then
down 120 feet then up another 50, you'll see a rise of 150 feet and a
fall of 120 feet.
I've received many requests, particularly from cyclists, for this
computation. But I've also heard that the resolution of the SRTM
elevation data doesn't give useful results -- see
http://www.heywhatsthat.com/testfaq.html#rise for a brief discussion
of the issue -- so now it's up to you to let me know if the results
are indeed useful.
MK
twitter.com/heywhatsthat
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